Mining in an account/balance blockchain system practically means finding a set of consistent valid transactions and applying them to the system state. For this activity we need two sub-functions: on the one hand the, transaction has to be validated against the state, on the other hand the transaction has to be applied to the state. For the sake of simplicity we assume that each block stored the whole state, which is copied one to one at the initializing the block.
For a simple transaction only setting data, the pseudo code is the following:
ValidateTransaction (Transaction t)
if t.signature is not valid
return error signature not valid
else
foreach account a in the state
if a.address == t.fromAddress
if a.nonce != t.nonce +1
return error replay attack
else
return transaction is valid
else
add new account to accounts with fromAddress
For a transaction transferring money:
ValidateTransaction (Transaction t)
if t.signature is not valid
return error signature not valid
else
foreach account a in the state
if a.address == t.fromAddress
if a.nonce != t.nonce +1
return error replay attack
else
if a.balance < t.amount
return balance is not enough
else
foreach account a in the state
if a.address == t.toAddress
return transaction is valid
add new account to accounts with toAddress
else
return error from account must exist at transferring money
For applying the state we have to iterate on all of the account check them if they are valid and after that apply the state change. It might vary again based on the exact type of the transaction. If it is a simple data transfer transaction:
ApplyState (Transaction t)
foreach account a in the state
if a.address == t.fromAddress
a.data = t.data
for the money transferring transaction it is a little bit more complicated
ApplyState (Transaction t)
foreach account a in the state
if a.address == t.fromAddress
a.balance -= t.amount
foreach account a in the state
if a.address == t.toAddress
a.balance = t.amount
